Ban assault weapons and buy them back. It might cost $15 billion, but we can afford it. Consider it an investment in our most important right, the right to live.

Andrew Norris, of Monroe, Ga.,participates in a gun-rights rally at the state capitol, Saturday, April 14, 2018, in Atlanta. About 40 gun rights supporters have gathered for one of dozens of rallies planned at statehouses across the U.S.(Photo: AP)

Gary was 28 and working as a security guard at a taco truck in Oakland, Calif., in 2009 when he saw Dreshawn Lee carrying a sawed-off shotgun and reported it to police. Three months later, Lee took his revenge by shooting and killing Jackson with an AK-47-style semiautomatic assault rifle.

I was the prosecutor who persuaded a jury to convict Lee and persuaded a judge to put him away for 65 years to life. But Gary’s autopsy report still haunts me.

Trauma surgeons and coroners will tell you the high-velocity bullet fired from a military-style, semiautomatic assault weapon moves almost three times as fast as a 9mm handgun bullet, delivering far more energy. The bullets create cavities through the victim, wrecking a wider swath of tissue, organs and blood vessels. And a low-recoil weapon with a higher-capacity magazine means more of these deadlier bullets can be fired accurately and quickly without reloading.

An assault weapon, then, is a hand-held weapon of war, capable of spraying a crowd with more lethal fire in seconds.

So Gary didn’t stand much chance. First-graders and teachers in Newtown, Conn., didn’t either. Nor did dancers at the Pulse nightclub in Orlando, nor concert-goers in Las Vegas, nor teenagers at Marjory Stoneman Douglas High in Parkland, Fla., nor the people at the Waffle House outside Nashville. Like so many American mass-shooting victims in recent decades, their doom was all but assured by the murderer’s tool.

Nonetheless, we can give ourselves and our children the chance these victims never had. We can finally act to remove weapons designed for war from our streets, once and for all.

Reinstating the federal assault weapons ban that was in effect from 1994 to 2004 would prohibit manufacture and sales, but it would not affect weapons already possessed. This would leave millions of assault weapons in our communities for decades to come.

Instead, we should ban possession of military-style semiautomatic assault weapons, we should buy back such weapons from all who choose to abide by the law, and we should criminally prosecute any who choose to defy it by keeping their weapons. The ban would not apply to law enforcement agencies or shooting clubs.

There's something new and different about the surviving Parkland high schoolers’ demands. They dismiss the moral equivalence we’ve made for far too long regarding the Second Amendment. I've been guilty of it myself, telling constituents and reporters that “we can protect the Second Amendment and protect lives.”

The Parkland teens have taught us there is no right more important than every student’s right to come home after class. The right to live is supreme over any other.

Our courts haven’t found a constitutional right to have assault weapons, anyway. When the Supreme Court held in 2008 that the Second Amendment protects an individual right to possess a firearm, Justice Antonin Scalia wrote that this right “is not unlimited” and is “not a right to keep and carry any weapon whatsoever in any manner whatsoever and for whatever purpose.”

Since that District of Columbia v. Heller decision, four federal appeals courts have upheld assault weapons bans. Many other firearms are available for self-protection, they found, and the danger that assault weapons pose to society is a legitimate reason for states and localities to ban them.

Australia got it right. After a man used military-style weapons to kill 35 people in April 1996, that nation adopted strict new measures and bought back 643,726 newly illegal rifles and shotguns at market value. The cost — an estimated $230 million in U.S. dollars at the time — was funded by a temporary 0.2% tax levy on national health insurance.

America won’t get off that cheaply. Gun ownership runs so deep that we don’t even know how many military-style semiautomatic rifles are in U.S. civilian hands.

Based on manufacturing figures and other indirect data, there could be 15 million assault weapons out there. If we offer $200 to buy back each weapon — as many local governments have — then it would cost about $3 billion; at $1,000 each, the cost would be about $15 billion.

It’s no small sum. But let’s put it in context.

The federal government is spending an estimated $4 trillion this year; $15 billion would be 0.375% of that, not that we must spend it all in one year.

Meanwhile, the GOP’s tax “reform” — a giveaway to corporations and the rich that threw comparatively meager scraps to working families — is projected to increase the national debt by $1.9 trillion over the next decade.

What is it worth to American taxpayers to not see our families, friends and neighbors cut down in a hail of gunfire? Consider this an investment in averting carnage and heartache and loss.

When I think of Jackson, I think of all the others who died with wounds like his. I think about my dad and two brothers who put their lives on the line as law enforcement officers. I think about my 11-month-old son, Nelson, and the safe classrooms I want him to learn in.

America has a deadly problem, a problem other developed nations have avoided or addressed. Some say we’re already too far gone to take corrective action, but we cannot have a defeatist attitude about this. Fixing our problem requires boldness and will be costly, but the cost of letting it fester will be far higher — for our wallets, and for our souls.

Rep. Eric Swalwell, a Democrat from California’s San Francisco Bay area, is co-chair of the House Democratic Steering and Policy Committee, and serves on the House Judiciary Committee and the House Permanent Select Committee on Intelligence. Follow him on Twitter: @RepSwalwell